jezter

I have had about the same issue over the last few years and it's ugly head has reared up once again... I had the fuel system redone less than two years ago by a shop but had issues with it and they shut down before fixing it right... they replaced the fuel switch and both tank pumps but the rear one never would work right... the truck ran fine and then started messing up again so I replaced most all the main parts around the motor but soon gave up... I decided to take it to a mechanic that has worked for Ford for 30+ years and races them... he found out that the rear pump was indeed bad, the front pump went out, the fuel switch on the rail was missing parts, and the electrical was messed up to the pumps... instead of forking out several hundred for the fuel switch, I had him bypass it and just have it run off the front pump... the truck has ran great until now...

a week ago it started sputtering and acting up again and has since gotten worse... at cold start it will start up and then shutoff immediately... I have to give it gas and then start it up and keep it reved up because it will not idle... over the last few days I have been having to run it much higher RPMs each day to keep it running until it warms up... it has gone from running about 1000RPM to 1500RPM to 2000RPM today... if it goes any less than it sputters and tries to die until it warms up... once it warms up (mainly after a good 10 min or so), it will idle but will constantly change, like a romping effect, between about 600RPM to 900RPM... it also likes to randomly sputter from time to time as you are trying to drive...

sorry for such a long explanation but this is my first post and want to make sure I get out all my information... it is acting similar to what happened before the other repairs but different as well... I am perplexed by it... any ideas???

Welder7018

Change your fuel filter. What's your fuel pressure?

jezter

I will check the fuel filter tomorrow... I do not have a fuel pressure gauge but plan on getting one tomorrow as well... I have checked the fuel rail and pressed the release valve while it was running and it shot out all the way to the hood... when off it seems to have the same pressure that it usually does when it was running correctly... so we will see... what is the pressure supposed to be exactly and at what times should I check it?

Welder7018

I think around 30-40 but not 100% sure on that

jezter

thanks for the information... I rented a fuel pressure gauge and finally got it to work... I am getting about 32-34 psi at idle and of course more when rev up... with the engine turned off, the psi does slowly back down and then goes back to normal when starting... so it looks like my fuel pressure is good... where to look from here is a question am I confused about... could a bad temperature sensor be causing it or something? bad injector perhaps? I dunno... any more thoughts???

Welder7018

Possible it's an injector. But I was certain it was a fuel pressure problem. But since its in the 30-40psi range it's good. I'm not sure what a temp sensor would have to do with the fuel delivery system. But it's a cheaper fix than an injector. Injectors are $200+ for a good set.

jezter

I have read somewhere before that if like the coolant temperature sensor is not working correctly the computer will send funny codes and such to everything else causing it not to run correctly... however that is one of the parts I have replaced in the last few years but am not sure if there are any other temp sensors... if it is not the fuel system or temp sensors, are the fuel injectors all that remains? I know the one on the front right (I believe) has been making a loud ticking noise... I am used to working on carburetor systems and not much with fuel injected ones...

Welder7018

If its making it constantly its bad. Mine does it when it's a cold start. It could also be a short or your air intake temp sensor.

jezter

I have noticed that if I move the large batch of wiring that every once in a while the idle will change some... but I have never tracked down what wire might be causing that or anything... I might check out that air intake sensor because I dont think I have ever changed that...

tdcarter72

Your truck don't have a air intake sensor.

You really need to pull the codes for your truck if you want to fix the problem instead of throwing money and parts on it that you don't need.

Here is a link to a very good and cheap code reader for our OBDI trucks


In the mean time I would start by unplugging and checking the connections on the sensors on the motor with it running. Might get lucky and find one not making a good connection.